non-POSIX variable name in Makefile.am

[bdrung]

autoreconf 2.69-11 (on Debian unstable) produces some warnings:

Makefile.am:17: warning: wildcard scripts/*: non-POSIX variable name
Makefile.am:17: (probably a GNU make extension)
complib/Makefile.am:20: warning: shell grep LIBVERSION= $(srcdir: non-POSIX variable name
complib/Makefile.am:20: (probably a GNU make extension)
complib/Makefile.am: installing 'config/depcomp'
libopensm/Makefile.am:20: warning: shell grep LIBVERSION= $(srcdir: non-POSIX variable name
libopensm/Makefile.am:20: (probably a GNU make extension)
libvendor/Makefile.am:22: warning: shell grep LIBVERSION= $(srcdir: non-POSIX variable name
libvendor/Makefile.am:22: (probably a GNU make extension)
opensm/Makefile.am:47: warning: ':='-style assignments are not portable
configure.ac: installing 'config/ylwrap'
osmeventplugin/Makefile.am:21: warning: shell grep LIBVERSION= $(srcdir: non-POSIX variable name
osmeventplugin/Makefile.am:21: (probably a GNU make extension)